There is an erasing apparatus which erases an image that has been printed on a sheet with erasable toner or ink, by heating the sheet to a temperature higher than a predetermined temperature, in order to reuse the sheet.
In some cases, an erasing apparatus includes a reading unit to digitize an image on a sheet before erasing and store the image. The stored image may be used to determine the presence of some image left after erasing and then to separate a reusable sheet and a non-reusable sheet. This erasing apparatus includes a cycle path for a reading unit performing the digitization and separation after erasing. The cycle path branches from a main path (i.e., a path from a sheet feed tray to a discharge tray) on the downstream side in the sheet carrying direction from the reading unit, and merges into the main path on the upstream side in the sheet carrying direction from the reading unit. The cycle path includes an erasing unit.
The operation of this erasing apparatus will be described. The reading unit reads a sheet supplied from a sheet supply unit and digitizes it. The sheet enters the cycle path and the erasing unit erases the image on the sheet by heating the sheet. Then, the sheet enters the main path and the reading unit reads the sheet again. According to the result of subsequent reading, the sheet is conveyed to a reusable tray or a non-reusable tray.
The temperature of the surface of a sheet gets higher after passing through the erasing unit. When the reading unit reads the heated sheet, the heat may introduce noise and/or hasten the deterioration of the reading unit. A fan may be installed between the erasing unit and the reading unit. The fan cools the sheet passing through the path while blowing air. However, because the fan is between the erasing unit and the reading unit, cooling air from the fan also goes to the erasing unit along the path. As the result, the temperature of the erasing unit drops, which may cause an erasing failure.